To avoid direct contact of the straps with the lifting hooks or other suspension fittings, which often cause deformation of the straps and considerable local stresses and premature wear, the ends of the straps, and particularly lifting and securing straps, are generally fitted with end-pieces for ensuring the functional connection between the strap and the suspension element.
The means for connecting these end-pieces to the lifting apparatus or similar consist generally of a round ring, an oblong ring, a suspension clevis, a so-called swivelling pivot eye, a hook, a shackle, etc . . . , whereas the connection with the strap is most often formed by a straight beam around which the strap is folded back on itself, the active strand being held against the return strand by stitching.
The loop of the strap thus formed may in particular be engaged on the transverse pin of a clevis which comprises for this purpose the end-piece. But most frequently the strap is disposed on a closed ring comprising a flat base.
A first disadvantage of such an arrangement is that the strap fitted with such an end-piece has a predetermined length which cannot be modified; furthermore, the stitching reduces the strength of the strap which must be consequently chosen so that its breaking strength is greater than that which would be required if it did not comprise such stitching.
There have also been proposed strap tensioners comprising three shafts aligned on a support, the active strand passing over the first shaft, then being wound in a figure of eight around the other two shafts, thus forming triple locking of the return strand, which obviously makes it impossible to adjust the length of the strap.